// Copyright 2021-2025 The Connect Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import { Code } from "../code.js";
import { ConnectError } from "../connect-error.js";

/**
 * Parse a gRPC Timeout (Deadline) header.
 *
 * @private Internal code, does not follow semantic versioning.
 */
export function parseTimeout(
  value: string | null,
  maxTimeoutMs: number,
):
  | { timeoutMs?: number; error?: undefined }
  | { timeoutMs?: number; error: ConnectError } {
  if (value === null) {
    return {};
  }
  const results = /^(\d{1,8})([HMSmun])$/.exec(value);
  if (results === null) {
    return {
      error: new ConnectError(
        `protocol error: invalid grpc timeout value: ${value}`,
        Code.InvalidArgument,
      ),
    };
  }
  const unitToMultiplicand = {
    H: 60 * 60 * 1000, // hour
    M: 60 * 1000, // minute
    S: 1000, // second
    m: 1, // millisecond
    u: 0.001, // microsecond
    n: 0.000001, // nanosecond
  };
  const timeoutMs =
    unitToMultiplicand[results[2] as keyof typeof unitToMultiplicand] *
    parseInt(results[1]);
  if (timeoutMs > maxTimeoutMs) {
    return {
      timeoutMs: timeoutMs,
      error: new ConnectError(
        `timeout ${timeoutMs}ms must be <= ${maxTimeoutMs}`,
        Code.InvalidArgument,
      ),
    };
  }
  return {
    timeoutMs,
  };
}
